Electric resistor



Nov. 1, 1955 G. J. MUCHER 2,722,585

ELECTRIC RESISTOR Filed Aug. 2, 1952 I 90 6 H $2 mm I 35 INVENTOR.

31 BY fiew- 'ef Mun/m1 United States Patent 9 ELECTRIC RESISTOR George J. Mucher, Rochester, N. H., assignor to Clarostat Mfg. Co., Inc., Dover, N. H., a corporation of New York Application August 2, 1952, Serial No. 302,449

Claims. (Cl. 201-55) This invention relates to a structure to be embodied in an electrical control and by means of which structure improved results are obtained.

It is a primary object of the invention to furnish an assembly by means of which the resistance element and the collector ring of an electrical control are properly positioned and maintained.

A further object is that of providing a design which will reduce the danger of current leakage and will also serve to assure uniform current flows under identical settings of the duplicate controls.

Still another object is that of providing a control structure of simple design which may be readily produced and the parts of which may be assembled with the expenditure of minimum effort and time.

With these and other objects in mind, reference is had to the attached sheet of drawings illustrating practical embodiments of the invention and in which:

Fig. 1 is a sectional side view of a control embodying the present teachings;

Fig. 2 is a sectional face view taken along the line 2--2 and in the direction of the arrows as indicated in Fig. 1;

Fig. 3 is an exploded perspective view of the main parts providing the stationary portions of the assembly;

Fig. 4 is a reverse view of the resistance and the mounting therefor as included in the present structure;

Fig. 5 is a fragmentary face view showing an alternative form of structure over that shown in Fig. 4; and

Fig. 6 is a sectional view taken along the line 66 and in the direction of the arrows as indicated in Fig. 5.

Referring primarily to Fig. l, the numeral 10 indicates an operating shaft which is rotatably supported within a bushing 11 and may be retained against axial movement in one direction with respect to the latter by means of a split ring 12 or other desired expedient. The inner end of shaft 10 provides a non-circular portion 13 which extends through openings of corresponding outline formed in an insulating disk 14 and a stop plate 15 which are secured to this shaft portion by conveniently heading over the extreme end of the same. Stop plate 15 preferably embraces an outward extension 16 cooperating with an inwardly extending portion forming a part of the cover of the assembly as shown in dot and dash lines in Fig. l. Suitably secured against movement with respect to plate or disk 14 is a conducting member 17 which may take the form of a ring. This unit has extending from it spring arms 18 terminating in contacts to traverse a resistance and further arms 19 terminating in contacts to engage a wiper ring.

A resistance of any desired character may form a part of the control. Conveniently, it includes a coated strip or element 20 having a diameter corresponding to the path traversed by arms 18. A collector ring 21 has a diameter corresponding to the path defined by the Wiper arm or arms 19. Preferably integral with ring 21 is an extension 22 continued in the form of a terminal 23. Terminals 24 are connected one to each of the ends of resistance 20. Resistance strip 20 is supported upon or Patented Nov. 1, 1955 Ice bears against an insulating body 25 conveniently of ring shape and which is in turn supported by a backing plate 26 preferably formed of metal. That plate is as shown secured to bushing 11. The extension 22 of terminal 23 and ring 21 projects through openings and notches forming a part of the insulating body or mounting 25. The terminals 24 are likewise secured to that body and in turn retain resistance strip 20 with respect to the same.

Interposed between the rotor assembly and the insulating support 25 is a unit in the form of a washer 27 constructed of non-conducting material. This washer presents on one face an upstanding collar or flange 28 encircling and defining its central aperture. The edge of the washer is formed with a suitable number of notches 29. As shown especially in Fig. 4, these notches, in addition to extending through the entire periphery of the washer, also communicate with recesses 30 presenting bearing surfaces formed in the body of that periphery to one side of the notches. At this time, it is to be noted that the collar or flange 28, while being preferably continuous as shown, might be interrupted if desired at any suitable number of points. In many respects it is preferred to have it continuous in that it will serve the function of a barrier where so constructed. Also as shown, various surfaces of the washer may be knurled while others may be smooth. This will enable the operator either visually or by touch to locate the washer in desired position within the assembly. It is again apparent that these surfaces might be modified as desired.

The resistance strip 20 is formed with inwardly extending projections 31. These spacing and areas of the latter correspond to the notches 29. Therefore, the washer may be passed through the space defined by the resistance strip or element with the protrusions 31 permitting of this by movement through these notches. With the projections 31 disposed in line with the periphery of washer 27 at points intermediate the side faces of the latter, that washer may be turned in a counterclockwise direction as viewed in Fig. 4. With such turning, the projecting portions 31 will be received within notches 30 and engage the bearing surfaces furnished thereby. Under these circumstances, the washer will be retained against axial displacement.

As in Figs. 5 and 6 a resistance element 20 corresponding in structure to that aforedescribed may be used. The washer 32 in this instance will be formed with notches 33 corresponding to notches 29. However, the entrance to the recesses 34 receiving the protuberances 31 will be defined by inclined surfaces terminating in shoulder portions. These, in effect, will furnish latches. Therefore, with the same turning of the washer effected with respect to the resistance, it follows that the projections 31 will cam over the surfaces 35 and ride into the spaces 34 to be retained therein against any accidental subsequent turning of the washer. With the latching action effected as the projections ride over the shoulders at the ends of surfaces 35 the operator would be aware that the parts have assumed their proper relative positions.

By bearing against the resistance strip, the washer serves to retain the same in proper position against the face of insulating ring or disk 25. Thus, any tendency of the resistance strip to curl or warp will be prevented and the strip will receive proper support independent of that offered by the terminals 24. This washer through its collar 28 or equivalent structure also provides a proper bearing surface in contact with the inner face of the insulating disk 14. Additionally, it properly supports the collector ring 21, and also serves to maintain that ring in properly centered position by means of the flange 28 or its equivalent.

Accordingly, the collector ring does not have to depend for centralization upon its extended terminal portion as heretofore resorted to. Additionally by means of an element such as the Washer, it is practicable to provide a preliminary or sub assembly and only thereafter apply the washer over the shaft. By such an expedient, the rotor may be inserted prior to the time that all elements are brought together. Aside from avoiding damage to the parts, this enables an operator to more readily complete the assembly.

Thus, among others, the several objects of the invention are shown; obviously, numerous changes in the structure and rearrangement of the parts might be resorted to without departing from the spirit of the invention as defined by the claims.

I claim:

1. A sub-assembly for use in an electrical control, said assembly including in combination a collar member, a resistance member encircling the same, one of said members being formed with a notch in that edge which is adjacent the other member and with a bearing face to ing surface and prevent movement of said members away from each other.

2. An assembly as specified in claim 1, such collar member being formed with a plurality of notches and the bearing surfaces to one side of the same, said resistance member being formed with a corresponding number of projections, each to enter one of said notches and to engage adjacent bearing surfaces.

3. An assembly as specified in claim 1, and latch means forming parts of said members, said latch means cooperating as said bearing surface is engaged by said projection to resist relative rotation of said members in a direction reversed to that aforenamed.

4. An assembly as specified in claim 1, said notch being formed in said collar member and a collector ring overlying said one face of said member and obstructing the notch formed therein.

5. An assembly as specified in claim 4, an insulating body underlying said resistance member and also formed with a notch and an extension of said collector ring extending from the latter, past said collar and resistance member and through the notch of said insulating body.

References Cited in the file of this patent UNITED STATES PATENTS 2,151,625 Thompson Mar. 21, 1939 

